ODOT and WSDOT are over-estimating future traffic on the I-5 bridge because they’re over stated the willingness to pay for travel time savings
The result will be an under-utilized, over-built I-5 bridge, and congestion on I-205
Over-estimating the willingness to pay for travel time savings causes IBR to underestimate diversion and negative environmental effects from tolling I-5
Metro’s case for a $7.5 billion Interstate Bridge rests on a critical assumption that doesn’t survive serious scrutiny: how much local drivers value their time. This seemingly technical detail has massive implications for the entire project’s justification.
There are currently no tolled roads in the Portland area. Drivers react to tolls in an unsurprising way: if a road is tolled, drivers tend to use it less. That’s a key feature of the IBR project: project proponents count on tolling to manage the flow of traffic over a much expanded I-5 bridge. Without tolls, the phenomenon of induced demand means that a wider bridge would simply generate even more traffic, more pollution and more congestion. Project proponents claim that a tolled, but much larger bridge would attract less traffic. How much less?